Los Angeles -LRB- CNN -RRB- -- Elvira Sosa left Mexico for the United States more than 30 years ago , but last year was the first time she 'd been counted as part of the U.S. Census .

Sosa was among thousands of illegal immigrants in Los Angeles who filled out a census form last year , and city officials said the response , especially among Latinos , might have saved the area money and congressional representation .

The increased count was purposeful : A Census Bureau outreach program urged undocumented workers to fill out the census and assured them that nothing on the form could be used against them .

The program included Spanish call centers that would field questions about the census , plus billboards , bus advertisements and fliers with information . Celebrities publicized the census , too .

The response : The 2010 census showed that the numbers of Latinos living in this country increased by 43 % , from 35 million to more than 50 million , during the past 10 years .

Arturo Vargas , executive director of the National Association of Latino Elected and Appointed Officials Educational Fund , testified before a Senate subcommittee this month that Latino participation in the census was `` unprecedented . '' But in some areas , poor communication , hostility toward Latinos and immigrants and a cultural fear of the government prevented a complete count , he said .

In Sosa 's case , her daughter encouraged her to fill out the form .

`` It 's important to count me , '' Sosa said in broken English , `` because I 'm important . I live in this country . ''

Mayor Antonio Villaraigosa was thrilled by Los Angeles ' mail participation rate . At more than 70 % , he said , it was among the highest for large cities and close to the national mail participation rate of 74 % .

More important , it might have secured money and political clout for the area . The Census Bureau uses population counts to apportion seats in the House of Representatives , and the federal government uses decennial census data to distribute more than $ 400 billion a year .

`` The last time around , 10 years ago , we were the second-worst among big cities in the country in terms of the undercount , '' Villaraigosa said .

The 2000 undercount cost Los Angeles more than $ 200 million in federal funds . Villaraigosa believes the outreach to the Latino and immigrant communities and the homeless population account for Los Angeles ' 2010 response success .

The National Association of Latino Elected and Appointed Officials said each person in the United States , legal or not , is worth about $ 1,400 in federal funds to a community per year .

Cities use these federal dollars to help pay for police and fire protection , along with vital infrastructure and other services .

It is illegal , however , to use federal dollars to aid illegal immigrants directly , and they can not receive government assistance . Instead , religious and other organizations fill the void . At the Margaret Aylward Center for the Poor in the Hispanic-heavy L.A. suburb of Pico Rivera , the size of the Latino population was clear well before it was counted by the census .

Sister Vickey Haran said the center relies solely on donations ; if she accepted government funding , she 'd be required to ask those seeking help from the center to prove their residency status .

`` It 's a ministry to the poor , '' said Haran , who runs the center along with the Holy Faith Sisters . `` We serve anyone who comes and asks for food . We do not ask for papers . We do not ask any proof . ''

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The count is about more than money and resources , though .

Villaraigosa said California would have lost a congressional seat if this census count remained at or near the same as in 2000 . That seat was saved , he said , because more people were counted .

`` What this does is , at a minimum , it allows California and other states with large immigrant populations to get the representation they deserve , '' Villaraigosa said .

But knowing that illegal immigrants might help to maintain the political power for a city or district raises the ire of some anti-immigration groups .

`` You have an imbalance , '' said Glenn Spencer , founder of American Patrol . `` You might have a congressional district in Los Angeles of 600,000 people but only 100,000 citizens . So those citizens have five times the voting power of someone in Iowa . You 'll have politicians who say ' I want these people counted . I get more power , but I can manipulate the situation because they ca n't vote . ' ''

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Census : Latinos living in U.S. increased by 43 percent , from 35 million to 50 million

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An outreach program in L.A. urged illegal immigrants to fill out census

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L.A. mayor said the increase in responses saved a congressional seat for California